Cartilage is a very specialized tissue containing only one cell type, the chondrocyte.[unreadable] Chondrocyte metabolism and function are influenced by the composition of the extracellular environment (Oxygen tension, pH, ionic concentration), the extracellular matrix composition, the matrix-cell interactions and the physical signals (stress and stain) transmitted across the articular surfaces of the joint. [unreadable] [unreadable] The failure of cartilage to regenerate itself is believed to be one of the fundamental pathways in the pathophysiology of degenerative osteoarthritis. [unreadable] [unreadable] The goals of this study are:[unreadable] [unreadable] - to determine the utility of non-invasive imaging techniques for early detection and longitudinal progression of age-related degenerative joint disease in a non-human primate model for spontaneous osteoarthritis; and[unreadable] - to examine the reparative potential of chondrocytes taken from aging non-human primates at various stages of joint degeneration. [unreadable] [unreadable] Progress during the past year:[unreadable] To date, 72 non-human primate knees have been collected from the NIH tissue bank.[unreadable] More than 50% of the specimens have been imaged by micro-CT and micro-MRI.[unreadable] These results indicate that micro-MRI and micro-CT can be used to detect early degenerative changes in NHP knee articular cartilage and subchondral bone respectively. These imaging modalities are also valuable in the long-term studies of the rate of disease progression, to quantify joint destruction, osteophyte formation and changes in bone mineral density in the non-human primate model for spontaneous OA.[unreadable] [unreadable] During the past year, we have concentrated our efforts towards determining the volume of knee articular cartilage in the aging NHP, and to correlate these findings with the respective subchondral bone mineral density.[unreadable] [unreadable] Our future goal is to complete the evaluation of the above studies, and to correlate our findings with quantitative measurements of serum biomarkers.